During the washing process of laundry in mechanical washing machines the laundry is first washed with water containing detergent and then drained and rinsed one or several times with rinse water. This rinse treatment is usually of a short duration. During this rinsing treatment use is frequently made, particularly in the last rinse step, of agents which are intended to impart improved properties to the washed laundry, such as a soft and fleecy feel, antistatic behavior, an antimicrobe protection and a pleasant smell. In order to be suitable for these finishing treatment methods, these agents must not only become uniformly distributed in the cold rinsing bath, but also become exhausted in a short time from the bath onto the textiles. Useful products are indeed on the market, which impart to the laundry in the last rinsing bath the desired, predominantly softening and antistatic properties, but all the items of laundry are uniformly affected by this type of treatment, so that the laundry must be sorted out already before washing with a view toward the finishing treatment. Moreover, care must be taken with this method that the finishing treatment agent is introduced into the washing machine at the correct time or through a special metering device and without contact with the actual washing agent.
A further disadvantage of the known laundry finishing treatment agents is that they can be made up only as highly diluted, aqueous suspensions, since stability during storage, ease of pouring and rapid distribution in the cold rinsing water is assured only when the effective substances are present in a dilution of 10 to 20 times, which leads to relatively high costs for packaging and transportation. Substances which are insoluble in cold water are just as poorly suited for this kind of laundry treatment as those which possess no specific affinity for the textile fiber surface, both are poorly exhausted from the rinse water and, consequently, with the used rinsing water, are passed to the sewer system. Therefore, the number of usable effective substances is limited.
With the steadily increasing use of laundry drying machines in industrial laundries and in private households, because of the saving in space and time in laundry drying afforded by such use by comparison with hanging the laundry on a line to dry, new possibilities now arise for moving the process of laundry finishing treatment to the drier itself and carrying it out simultaneously with the drying of the laundry. Recently, a series of proposals have, therefore, been made as to how known and new effective substances can be applied to the finishing treatment of laundry in the laundry drier. Among these proposals are the use of textile or paper webs which are impregnated with the effective substance, as described in U.S. Pat. Nos. 3,632,396, 3,686,025 and 3,743,534, and the use of foaming or non-foaming aerosol mixtures, with which the effective substances are sprayed onto the internal wall of the drier or onto the moist textile articles.
Furthermore, the use of perforated hollow objects, which contain a solution of the effective substance and which are tumbled in the laundry drier together with the laundry, as described in U.S. Pat. No. 4,014,105, and of solid, pelletized mixtures of the effective substances with soluble carrier substances, which are to be absorbed during the drying process onto the textile surface, has also been discussed. These forms of application of the state of the art are, however, accompanied by a series of disadvantages. Thus, for example, a non-uniform distribution and a consequent forming of stains on the laundry are observed in the use of solid textile softeners. Even with the perforated hollow articles filled with liquid finishing treatment agents, the problem of the uniform distribution of the effective substances is not solved, added to which are the further disadvantages of the cumbersomeness of these articles and the difficulty of metering the effective substances. With the use of the agent in spray form, undesired precipitations frequently form on the equipment parts important for correct functioning of the laundry drier equipment, such as, for example, the temperature and humidity sensors. With the sheets of paper, woven or non-woven fabric impregnated with the effective substance, it is to be observed that the effective substance adhering to the substrate, which should become detached from the substrate and absorbed onto the textile to be dried, is only incompletely given off due to the fact that these structures, which have a large surface area, tend to cling to the wall of the dryer drum or to a piece of the laundry, which also imposes a limit upon the effectiveness of this form of application.
U.S. Pat. No. 3,701,202 discloses another method of distributing liquid textile treating agents in a drum dryer which comprises a container with a porous outlet which is clamped in the rotatable drum. This likewise creates problems of uneven distribution of the treating agents and involves the additional problem of detaching and replacing the container after each operation or after several operations, in order to fill the same.
Another commercial development of the same nature is the use of a porous container which has a self-adhering side, which is attached to the wall of the dryer drum, as is described in U.S. Pat. No. 4,004,685. This type of device presents the problem of even application of the treating agents to the goods, particularly since the commercial embodiment is designed to be used over a series of drier cycles.
U.S. Pat. No. 3,989,638 likewise is directed to the problem and discloses the use of articles releasably containing starch-thickened peroxygen bleaches for use in machine laundry driers. Patentee employs articles having perforations in the range of 0.05 to about 3 mm in order that his thickened bleaches can be released at the proper rate, since moisture must be present to effect the bleaching action. This device suffers the drawback that the amount of bleach being dispensed at the onset will depend on the temperature of the bleach package storage since the viscosity of the starch thickened bleach is dependent on viscosity. Moreover, such an article must be covered until the time of use and care must be taken to avoid loss of bleach from the article before inserting the same into the dryer.